When you have a cultural phenomenon on the horizon — much like Marvel Studios has with the yet-untitled Avengers 4 — every fan thinks they have the perfect idea on what's going to happen. While most fan theories are nothing more than wishful fan fiction, every so often something that pops almost seems too good to be true.
A new fan theory that cropped up on the MarvelStudios subreddit earlier today might be the most thorough theory we've seen yet, and it involves a character we haven't seen in quite some time being the key to The Avengers' success in defeating Thanos (Josh Brolin).
According to Reddit user
The theory states that since Selvig was under the sway of the Mind Stone as it was still contained in Loki's Scepter, it gave the scientist all of the necessary information about the events that were about to unfold. This hints that Selvig knew about "The Snap " causing half of the universe to disappear, and although they aren't necessarily dead, they aren't really alive either creating a Schrodinger's cat scenario.
It goes on to share that Selvig's notes from Thor: The Dark World can be deciphered into hinting at traveling across both space and time — thanks to the "Fractal Gateways Connecting
Essentially the theory states that Selvig knows The Snap was going to happen and create a fault in which the multiverse crashes in on itself. Because of the unnatural occasion, the theory states that the larger-than-life Cosmic entities — think the Living Tribunal or Master Order and Lord Chaos — are the threats bigger than Thanos in Avengers 4.
The theory then goes on to state that Thanos, feeling guilty about murdering his daughter so that he can complete his Gauntlet, will try snapping again to reverse the actions only for it
Avengers 4 is in theaters on May 3, 2019.